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Plants herbaceous rosettes with no stems, erect self-supporting and tree-like, or pendulous, or scrambling, or curtain-forming; rhizomes usually pachymorph, or leptomorph, or both. Culms absent or to 18m tall, caespitose, diffuse or pluricespitose; internodes usually solid, often hollow, terete or shallowly grooved above branches; nodes level or more or less swollen, the supranodal ridge obscure or well-developed, nodal line horizontal or diving well below branches. Branches completely absent, or initially 3, or up to several hundred, central and laterals equal, subequal, dimorphic or trimorphic, fully sheathed or with several to most sheaths much reduced, intravaginal, extravaginal, or infravaginal; buds absent, few, or multitudinous, at mid-culm often very open at front, prophylls usually absent, few to many subsidiary axes exposed, or higher orders of branching apparently from separate buds, or actually from many buds on opposite sides or all around the culm. Culm sheaths absent, or delicate and deciduous, or tough and persistent; blades deciduous or persistent, large and inflated to very small, articulating to scarcely defined, erect or reflexed. Leaf sheaths persistent or deciduous, delicate to greatly thickened; blades extremely long and broad to tiny and needle-like, with or without prominently tessellate venation, erect or deflexed. Synflorescence semelauctant, ebracteate, open and paniculate, or more dense, or tightly capitate. Spikelets with single florets; glumes (2)-4; lemmas blunt or mucronate; paleas unkeeled to 2-keeled, blunt, mucronate, or bimucronate; rhachilla extension absent; stamens 3; style with 2 plumose stigmas. Name from Chusque, the local name for species including the type species Chusquea scandens, in Colombia and Ecuador.
Chusquea is a New World tropical to temperate genus, currently interpreted very, very broadly indeed relative to other bamboos, largely on the basis of the criterion of molecular monophyly, and including in its 13 subgenera, sections and groups up to 200 species, found from NW Mexico across to E Brazil, the West Indies, and down to S Chile, from the coasts to the Andean summits. Included within it are at least 3 subgenera and 3 sections that would definitely be considered distinct genera if found in Asia, as well as 26 species in 7 more groups, all with unusual characters that cannot currently be placed in any subgenus or section. In terms of breadth of generic concept, Chusquea is similar to Arundinaria, before even the large groups Sinarundinaria and Thamnocalamus were recognized, not to mention the 15-20 genera that are currently recognized within them. However, the divisions within Chusquea are not as clearly defined, for various reasons, one of which though may be lack of study.
While some species are clearly bamboos, several species do not really look like bamboos at all, and from a distance could easily be mistaken as, for example, a reed, a dwarf conifer, a Sisyrinchium, or a Phormium, while in several species the whorls of short branches with narrow leaves right around the culm nodes can give the appearance of a giant horsetail.
There is in fact so much morphological diversity within Chusquea as currently circumscribed in this very broad sense, that it is impossible to generalise morphological characters at all, except for its spikelets, which are consistent in having only one floret. Thus the genus has practically no value for field identification, and 2-3 infrageneric ranks of subgenus section and group need to be used. To put it mildly, there would appear to be something of a mismatch between generic concepts that have evolved over centuries when describing bamboos in Asia and Europe, where a binomial system of genus and species is sufficient for identification, and in the Americas, where a 3-4 ranked system is now required. The older Asian classification system evolved in times when morpho-geographical criteria were followed and a pragmatic identification/documentation objective was paramount. Chusquea has been studied more recently, in times with different objectives. Thus it is best when referring to Chusquea species to always give the full subgeneric classification as well, where there is one.
Fortunately from the point of view of identification of cultivated plants, only a small number of species have made it into horticulture. This is partly because the number of truly hardy species of Chusquea is quite small, and most of the tender species are very demanding in their requirements. Many species are not well suited to cultivation simply because they are scramblers and not self-supporting, and have scruffy persistent sheaths. Others just don’t even look remotely like a traditional bamboo in the first place, so they have not been collected for cultivation as bamboos. In addition description and taxonomy of many Chusquea bamboos is not sufficiently advanced for the clear characterisation and separation of species.
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